witnesser vs percipient

witnesser and percipient both are nouns.

Word	Noun	Adjective	Verb	Adverb
witnesser	Yes	No	No	No
percipient	Yes	Yes	No	No

As nouns, percipient is a hypernym of witnesser; that is, percipient is a word with a broader meaning than witnesser:

witnesser: someone who sees an event and reports what happened
percipient: a person who becomes aware (of things or events) through the senses

Other hypernyms of witnesser include beholder, observer, perceiver, speaker, talker, utterer, verbaliser, verbalizer.

witnesser (noun)	percipient (noun)
someone who sees an event and reports what happened	a person who becomes aware (of things or events) through the senses

witnesser (adjective)	percipient (adjective)
	characterized by ease and quickness in perceiving